Craniofacial surgery can be used to correct a number of conditions of the jaw and face related to structure, growth, sleep apnea, correcting malocclusion problems owing to skeletal disharmonies or other orthodontic problems that cannot be easily treated with braces. During craniofacial surgery an osteotomy is often performed in which the bones can be cut, realigned, and held in place with either screws or plates and screws. Two craniofacial procedures that are performed to correct conditions of the jaw and face are maxillary advancement which can include maxillary distraction, and maxillary expansion which can include transpalatal distraction.
Maxillary advancement involves repositioning the maxilla bone of a patient so that it properly aligns with the mandible. Maxillary advancement can include the steps of performing a “Lefort I” osteotomy (resection of a maxilla from a remaining portion of a skull); moving the maxilla forward (or anteriorly); and reattaching the maxilla to the remaining portion of the skull using a bone plate and screws until the bone segments grow together and consolidate.
Reduction and distraction devices (commonly referred to as reducers and distractors), are used to gradually adjust the relative orientation and spacing of bone parts on opposing sides of an osteotomy. Reducers and distractors typically consist of transcutaneous pins or screws secured in the bone on either side of the osteotomy together with a mechanism that allows controlled incremental adjustment of the distance between parts of the distractor on opposing sides of the osteotomy and the bone segments the parts of the distractor are attached to. Typically, distractors are used to perform distraction osteogenesis (the formation of bone).
Maxillary distraction involves the use of a distractor to reposition the maxilla bone of a patient so that it properly aligns with the mandible. Maxillary distraction can be performed using a “Lefort I” osteotomy resecting the maxilla from the remaining portion of the skull, so that the skull is separated into two bone portions. Then, the bone portions on either side of the osteotomy may be gradually separated, for instance by actuation of a distractor, during a distraction phase. This gradual separation allows new bone to form in the osteotomy void between the two bone portions. The distraction phase is followed by a consolidation phase, during which the distractor is held fixed, and new bone growth gains strength. Following the consolidation phase, the distractor is removed from the patient.
Transpalatal distraction involves expanding the palatal region of the skull to correct such defects as maxillary constriction. Transpalatal distraction can be performed using a sagittal split osteotomy to form two bone segments of the maxilla, and inserting a transpalatal distractor which is expanded to widen the palate until a desired orientation of the two bone segments is achieved. Braces or other anchoring devices can be used to secure the palate in the desired shape until consolidation of the bone segments occurs.
Traditionally if both maxillary advancement and transpalatal distraction procedures are to be performed on a patient, the procedures are performed in two separate surgeries. For instance, referring to FIG. 1A, the skull 1 includes a maxilla 2 that forms the upper jaw region 3 of the skull 1 and holds the upper set of teeth 4. In some instances the skull 1 can be deformed as the result of disease, genetics, trauma, etc. If a deformity of the skull 1 is significant, surgery may be an appropriate option for correction. Surgical procedures exist to correct a number of different deformities in the skull 1. For example, maxillary advancement and maxillary expansion (such as transpalatal distraction) are two procedures used to correct misalignment in a patient's bite, such as an under bite or over bite, by altering the relative position and orientation of the maxilla 2 to the rest of the skull 1.
Referring to FIG. 1B, during a maxillary advancement procedure, a portion of the maxilla 2 is separated from the rest of the skull 1. This separation can be accomplished with a Lefort I osteotomy which is performed by cutting through the skull along medial-lateral and anterior-posterior directions so as to separate the maxilla 2 from a remaining portion 5 of the skull 1 along a cut line 6. Once the Lefort I osteotomy is complete the maxilla 2 can be repositioned, for instance advanced, in an anterior-posterior direction, as illustrated by arrow 7, to a desired position. One or more bone plates then secure the maxilla 2 to the remaining portion 5 of the skull 1 so as to fix the maxilla 2 in the desired position until the skull 1 has consolidated.
If the maxillary advancement procedure is a maxillary distraction procedure, once the Lefort I osteotomy is complete a distractor can be secured to the maxilla 2 and the remaining portion 5 of the skull 1 in approximately their original position and orientation. Actuation of the distractor then results in the maxilla 2 being repositioned, for instance advanced, in an anterior-posterior direction, as illustrated by arrow 7, to a desired position. The distractor can then keep the maxilla 2 secured to the remaining portion 5 of the skull 1 in the desired position until the skull 1 has consolidated.
Referring to FIG. 1C, once the skull 1 has consolidated, a second procedure, for instance a maxillary expansion, typically involves the surgeon performing a partial Lefort I osteotomy by cutting medial-laterally through the skull 1 and anterior-posteriorly through a portion of the skull 1 so as to leave the maxilla 2 attached to the remaining portion 5 of the skull 1 so as to define respective bone portions 12 that define hinges for the maxillary expansion procedure. After completion of the partial Lefort I osteotomy, the sagittal split osteotomy is performed by cutting the maxilla 2 along cut line 8 such that the maxilla 2 defines two bone segments 2a and 2b that are separated from the rest of the skull 1 and also separate from each other along the cut line 8. The surgeon can then place a palatal distractor between the two segments 2a and 2b of the maxilla 2 and use the palatal distractor to move the two segments 2a and 2b of the maxilla 2 in a medial-lateral direction, as shown by arrows 9, to a desired orientation. The distractors, or alternatively bone plates and fasteners, can then be used to reattach the two segments 2a and 2b of the maxilla 2 to the skull 1 in the desired orientation until the skull 1 has consolidated, rejoining the segments 2a and 2b of the maxilla 2 and the remaining portion 5 of the skull 1.